Boiler



June 25, 1929. .1 A. FREIDAY BOILER Filed March 12, 1927 7F Tl WM?INVENTOR Q/AYA. fifif/ /i/r fihATTOR/VEY Patented June 25, 1929.

1,718,345 PATENT OFFICE- UNITED STATES".

JAY A. FREIDAY, OF EAST ORANGE, NEW JERSEY, ASSIGNOR-TO THOMAS E.MURRAY, OF BROOKLYN, NEW YORK. i

BOILER.

Application filed March 12, 1927. Serial No. 174,736.

This invention aims to provide certain improvements applicableespecially to high duty boilers. .The accompanying drawing illustratesin a single figure a longitudinal vertical section of a boiler embodyingthe invention.

The boiler includes the usual overhead banks 1 and 2 of approximatelyhorizontal water tubes with headers 3 and 4 at the lower ends and 5 and6 at the upper ends connected to the steam drum 7 from which the steampasses through a superheater 8 to the point of consumption. Baffies 9,10 and 11 direct the gases in the desired course over and between theseveral tubes. This is a common arrangement and various modifications ofthat illu'strated may be utilized with this invention. v

It has been the constant effort of designers n to operate such boilersat higher and higher speeds or ratings, so as to get the maximumquantity of steam per hour out of a given installation,iand this hasinvolved extending the stoker or other fuel supply devices. To get themaximum stoker capacities this part of the apparatus has been extendedclear across to the back of the furnace or combustion chamber and evenbeyond the normal line of the back wall. My invention provides astructure which facilitates the use of such 30 an extended stoker. Thefront wall 12 of the furnace has a feed opening 13 adjacent to which isthe hopper 14 for coal and the feed mechanism indicated diagrammaticallyat 15 from which extends the stoker grate 16 sloping gradually downwardto the rear and dumping the ashes and cinders finally into an ash trough,17. In order that the stoker grate may be made as long as possible fromfront to back, I have provided a rear furnace wall 18 which is offsetconsiderably beyond the rear wall of the upper structure as marked bythe headers 5 and 6. The wall 18 extends vertically to about the topofthe combustion chamber where it meets an arch 19, the inner end of whichis curved inward as at 20 to provide for a certain amountof expansionand connects with the upper structure. This wall is exposed to very hightemperatures from the radiant heat of the burning fuel. I prefer toprotect it and at the same time'to utilize the heat to greatestadvantage by lining it with a wall of water tubes 20 extend ngvertically up the face of the vertical portion 18 and tubes 21 along theinner face of the portions 19 and '20. These tubes have head ers 22, 23and 24 in the locations indicated, the latter communicating with theheaders 5 so as to provide a direct and easy circulation of steam fromthe lower tubing to the steam drum; the cross header 25 at the frontwhich rece ves water from the steam drum, having outside connections asusual leading down to the drum 22 at the base of the rear wall. Theintermediate drum 23 may be omitted though it probably facilitatescirculation.

Such an offset Wall 18 and arch 19 (either with or without the waterlining) provides a very simple and convenient structure which permitsthe making of the stoker of maximum length. When the water tube liningis added we get an even more beneficial result from the increased stokersize, by reason of the effeet of the radiant heat on the water in thesetubes. It has previously been proposed to carry the dumping end of thestoker and the ashpit into .a shallow recess at the back of the furnace,practically the whole space for combustion and mixture of the gasesbeing of the a same cross-sectional area as that of the overhead tubingor less.

According to the present invention, how-v ever, the offset rear Wallextends to a considerable height above the rear end of the stoker andpractically to the rear ends of the overhead tubes, allowing only spaceat the top for the inclined arch and expansion bend, and extendingdownward well below the front wall. Thus we have a comparatively'highcombustion chamber of the full width of the overhead bank of the tubesand of greater length than such tubes throughout substantially the fullheight of the chamber, and of a greater height at the back than at the,front, so. as to effect thorough combustion and 'uniform admixture ofthe gasesbefore their passage through the overhead tubes.

The shape illustrated has also an advantage in connection with the ashpit at the base of the rear wall. A certain amount of cold air entersfrom the ash pit and is carried up in the current of gases. .With theshape illustrated, this cold air'is forced to take roughly the directionindicated by the dotted arrow, so that at the top, and before the hotgases strike the overhead tubing, they are deflected in an approximatelyhorizontal direction and distributed over the cross-section of thecolumn of hot gases. This crosscurrent also effects a mixing of thecombustion gases which improves the combustion n the combustion chamber.Where there is no such lateral movement of the cold air, it is apt to goup in a continuous channel. Coal dust firing and other methods ofintroducing fuel may also be used here with advantage in Variousmodifications ma be made by those skilled in the art wit out departingfrom the invention as defined in the following claims.

What I claim is 1. A boiler having approximately horizontal overheadtubing and a furnace with a high rear wall which is offset beyond therear ends of the overhead tubes, with an arch at the upper end of saidrear wall spanning the distance between it and the rear ends ofsaidoverhead tubes, said offset rear wall extending upward verticallypractically-to the rear ends of the overhead tubes and extendingdownward well below the level of the front wall and forming acomparatively high combustion chamber of the full width of the overheadbank of tubes, of reater length than said tubes throughout su stantiallythe full height of the chamber and of greaterdepth at the back than atthe front.

2. A boiler having approximately horizontal overhead tubing and afurnace having a comparatively hi h combustion chamber the rear wall ofwhich is vertical and offset beyond the rear ends of the overhead tubes,

with an arch at the upper end of said rear wall spanning the distancebetween it and the rear ends of said overhead tubes, incombination witha stoker extending from the front to the rear of the furnace, the offsetrear wall extending vertically ractically up to the rear ends of theover ead tubes'to form. a comparatively high combustion chamber of thefull width of said tubes and ,of greater length throughout substantiallythe full ases. g 3. A boiler havingapproximately horizontal overheadtubin and a furnace with a high rear wall which is offset be ond therear ends of the overhead tubes, wit an arch at the upper end of saidrear wall spanning the distance between it and the rear ends of saidoverhead tubes, said offset rear wall extending upward verticallypracticall to the rear ends of the overhead tubes an front wall andforming a comparatively high combustion chamber of the full width of theoverhead bank of tubes, of eater length than said tubes throughout sutantially the extending downward well below the level of the full heightof the chamber and of reater depth at the back than at the front, saidrear wall including vertical water tubes exposed to the radiantheat ofthe burning fuel. I

4. A boiler having approximately horizon- 7 tal overhead tubing and afurnace having a comparatively high combustion chamber the rear wall ofwhich is vertical and offset beyond the rear ends ofrthe overhead tubes,with an arch at the upper end of said rear Wall spanning the distancebetween it and the rear ends of said overhead tubes, in combination witha wall of vertical water tubes lining said'rear furnace wall and astoker extending from the front to the rear of the furnace so that saidtubes are exposed to the direct radiant heat of the burning fuel, theoffset rear wall extending vertically practically up to the rear ends ofthe overhead tubes to form a comparatively high combustion chamber ofthe full width of said tubes and of greater length throughoutsubstantially the full height of the chamber so as to effect thoroughcombustion and uniform admixture of the gases.

5. A boiler having approximately horizontal overhead tubing and afurnace having a comparatively high-combustion chamber the rear wall ofwhich is vertical and offset beyond the rear ends of the overhead tubes,05

with an arch at the upper end of said rear stantially the full height ofthe chamber so as to effect thorough combustion and uniform admixture ofthe gases.

6. A boiler having approximately horizontal overhead tubing and afurnace with a high rear wall which is offset beyond the rear ends ofthe overhead tubes, with an arch at'the upper end of said rear wallspanning the distance between it and the rear ends of said overheadtubes, said offset rear wallextending upward vertically practically tothe rear ends ofthe overhead tubes and extending downward well below thelevel of the front wall and forming a comparativelv high combustionchamber of the full width of the overhead bank of tubes, of greaterlengththan said tubes throughout substantially the full height of thechamber-and of greater depth at the back than at the front, said rear 1wall and arch including water .tubesextending from the bottom of thewall up to the rear end of the overhead tubes.

7. A boiler having approximately horizontaloverhead tubing and a furnacehaving j a comparatively high combustion chamber the rear wall of whichis vertical and offset beyond therear ends of the overhead tubes,

said rear wallincluding'vertical water tubes and a stoker extending fromthe front to the rear of the furnace so that said tubes are exposed tothe radiant heat of the burningfuel, the offset rear wall extendingvertically practically up to the rear ends of the overmy name.

JAY A. FREIDAY.

head tubes to form a comparatively high 10

